Come on, you don't even need the same DAW to work together with this one.
You don't see what the other one does, yet you hear it and, really, it's not hard to discover what root note the other guy is using. You can simply try it and find out if needed even.
This combined with - for example - msn messenger offers the feature of 'multiplayer producing' in a pretty acceptable way.

You just need to drop VSTunnel in your master channel btw, and it will stream it to your friend and do the same with what your friend has running.
It's been really long since I used this, so it's propably improved a lot by now.